Purpose :
To assess functional and structural progression after 48 months of treatment with ciliary neurotrophic factor (CNTF) delivered using an encapsulated cell implant for the treatment of macular telangiectasia (MacTel) Type 2.

Methods :
MacTel Type 2 affects both eyes and is characterized by retinal opacification, vascular telangiectasis, right-angle venules, intra-retinal crystalline deposits, foveal thinning, retinal pigment epithelial hypertrophy, and, in some cases, intra-/sub-retinal neovascularization. This neurodegenerative disease is considered to result from the loss of Mueller cells, resulting in loss of photoreceptors. A Phase 1 open label, non-randomized Phase 1 study was conducted to assess ocular safety after implantation of the CNTF-secreting capsule. Secondary efficacy outcomes included change in visual acuity, optical coherence tomography en face measurements of the disruption in the ellipsoid zone, and microperimetry comparisons between baseline and 48 months of treatment.